The invention relates to a process and an apparatus for operating an internal combustion engine which preferably includes an electronic fuel injection system and an air-flow measuring device. The fuel is metered out to the air in the induction tube in dependence on operational parameters of the internal combustion engine. The invention further relates to an apparatus for carrying out the process according to the invention.
In order to achieve optimum combustion of fuel in an internal combustion engine, a particular fuel quantity must be metered out to the aspirated air. The determination of the proper mixture ratio is based on consideration of engine parameters such as the engine temperature and the engine rpm. In known installations, these parameters are fed to an electronic injection controller which forms an output signal that controls the individual fuel injection valves. In that apparatus, the measurement of the aspirated air quantity presents a particular problem. Known air flow rate meters used for measuring the aspirated air quantity in the motor vehicle are usually embodied on the principle of baffle plates. A plate is movably disposed perpendicular to the direction of the air flow and is deflected by the air against the force of a spring, the air induction channel being conically enlarged in the general region of the baffle plate. The particular disadvantage of this apparatus is that the moving mechanical parts are subject to wear and the baffle plate offers high resistance to the air flow, thus decreasing the aspirated air quantity. It is also known to provide air flow rate meters for an internal combustion engine which generate ions at some location within the air induction channel. These ions continue to move with the aspirated air stream and are subsequently deviated from the air stream by magnetic or electric fields. The disadvantage of this known system is that the generation and deviation of the ions requires high electric potentials which increases the cost of the system as does the required electrical insulation of certain parts of the induction channel. Furthermore, it is difficult to provide shielding against electrical disturbances produced by the system and the sensitivity of the mechanism to dirt and moisture is quite high.